Internal mix spray gun



w. P. DALRYMPLE 2,518,759

INTERNAL MIX SPRAY GUN Filed Deo. 3, 1947 Aug. l5, 1950 imm" INVENTOR. `WILLIAM P. DALRYMPLE ATTORNEYS Patented Aug. 15, A1950 UNITED STATES PATENT OFFICE Y William P. Dalrymple, Rochester, N. Y.,.assignor to American Brake Shoe lCompany, New York,

N'. Y., a corporatonof'Delaware Applicationccember 3, 19471;;Serial No.789A8l 2 Claims. (iCl. 299-4401) This invention relates to spray guns of the type; utilized .for spraying paint and the like surface coating materials, and particularly the invention relates` to the kind of spray guns that have been termed internal mix guns.

In spray guns of the internal mix type-it has heretofore. been customary to discharge the mixture of air and paint from the internal mixing chamber into ya relatively long and narrow slot extended transversely of the discharge orifice of the spray head, and this. arrangement resultsv in the. production of a relatively long and narrow spray pattern which is.L desirable in most types of. paint supply work. In prior spray gunsv of the aforesaid character, this long narrow spray pattern. has been relatively xed in size and form so that such spray guns werev notv adapted Vfor use Where a smaller spray pattern was required. It is therefore an important .object of the present invention to enable the long and narrow spray pattern of such an internal.

mix spray gun toV .be variedas to form, andrelated objects are to enable the length ofV such a spray pattern to be. materially reduced.. and to` enable this to be Vdone. in a simple and expeditious manner. I r Y Other and further obiectsof the presentinvention will be apparent from the -following de.- scription. and claims and are .illustrated in. the accompanying drawings which, by way of illustration. show `a preferred embodiment and the principles thereof and what I now. consider to bev the bestl mode in which I. have contemplated applying those. principles.. Other embodiments of the invention. embodying theY same or equivalent principles maybe used andstructural changes may be madeA as desired by thoser skilled in the art without departing from the present .invention and the purview of thev appended' claims.

In the drawings:

Fig. 1 is a vertical sec-tional view taken through a spray gun embodying the features of the invention.

Fig.,2 isa front elevational Vview of the; spray head as viewed from the rightinl Fig. 1.

Fig. 3 is a, diagrammatic view illustrating the normal spray pattern attained by the spray' gun illustrated in Figs. 1 and 2; Aand Fig. 4 is a diagrammatic view illustrating a modified form of the spray pattern that may be attained with the spray gun of Figs. 1 and 2.

For purposes of disclosure the invention has been illustrated in Figs. 1 and 2 as embodied in a pistol-grip type of spray gun of the same general construction as the spray gun disclosed in my rsi:-

copending applioationSerial No. 734,819, led. March 14, 1947. This spray gun has a main body I Il with a downwardly extending handle. II. atV what may be termed the rear end. of this body. At the forward. end of thev body Ill, an adaptor fitting I2 is secured in place on the body Ill by' meansV including .a cap screw I3, and at the forwardr end of the vfitting, I2,.a spray head I5 embodying the present invention. is secured. in place.

I8 tapers toa reduced discharge end 22` that` is.

disposed within av mixing. and discharge orifice 24. formed in ther head I5. The orice 24- extends` forwardly and at its outer end opens into a nar- 1; row transverse slot 25 formed in the forward aforesaid` copending application, andv when the. L valve 2B is openedrthe paint is withdrawn or aspirated through the nozzle 22 by the passage of pressure, air about. the nozzle 22` and into-the discharge orifice 2.4.. Such pressureairv is supplied.

through a passage 32 formed in they handle I I .as described in my aforesaid copending application,v and amain valve 34 is. arrangedto control such1 air passage and is in turn controlledby the. main control lever 3U. 'I-he air which. passes the -main valve 34A is discharged upwardly through an adjustable sleeve valve 35 vand into a horizontal passage 36' that extends forwardly in` the bodyy Ill so as to open into the tting-IZ.v Atthe forward end of the tting, such air normally passes through a passage 31 and into an annular distributing groove 38 formed in the forward face of the fitting I2. From the annular distributing passage or groove 38, such air passes through angular bores 39 formed in the nozzle 20 and into a chamber 40 formed about the outer end portion of the nozzle 20 and within the head I5. It is the air that is thus supplied which acts to withdraw or aspirate the paint from the nozzle 22, and as the mixture of paint and air leaves the orifice 24 and passes through the transverse slot 25 the mixture is so directed that it normally assumes the relatively long and narrow spray pattern P-I as shown in Fig. 3, the long axis of the pattern P-I being parallel to the slot 25.

Under the present invention, this normal spray pattern may be modified in a simple man-- ner When this is desired, and to attain this re' sult, use is made of an adjustable control valve which forms a part of the spray gun ,illustrated in my aforesaid copending. application; the spray gun has a supplemental air passage 45 formed in the fitting i2 so as to communicate with the forward end of the passage 35. This passage 45 is controlled by a, needle Valve i5 that extends into the passage 35 and is adapted for adjustment by aknurled operating head il disposed at the -rear end of the body BEL The forward endof the passage YMiopens into an annularv distributing groove 4B formed in the for!- ward face of the fitting I2, and under v the present invention, the head I5 has anannular chamber 50 in -its rear face which communicates with the chamber 48.A From the annular chamber 5S,

the p air of passages 52 are formed in the planel of the slot 25 so that the forward ends of the passages 52 open into the slot 25 on opposite sides of the orifice 24. These passages 52 converge upon the axis of the Vorifice 24 so that when the valve 46 is opened, the air discharged from the passage 52 tends to reduce the length of the spray pattern P-l so that the pattern approaches the form indicated at P-2 in Fig. 4- of the drawings. The extent towhich the no rf mal spray patternP--i is thus modified is de -v pendent upon the adjustment of the supplemen-f tal control valveAB. In the normal use of the spray gun that is thus disclosed, the v aive 4E is maintained closed so that the elongated spray pattern P-I is attained, but when ashorter pattern is desired, the .valve is opened fprogressively until the length ofthe pattern has been reduced in the desired amount. Such v alve operation may of course b e easily accomplished, and hence by the present invention, an internal mix spray gun may bereadily employed even in those instances Where a relatively short spray pattern is to be required for some of th work that is to be done.

' From the foregoing description it will be ap;- parent that the present invention materially increases the eld of usefulness of an internal mix spray gun, and more specifically it will be evident that under the present invention the spray pattern of an internal mix gun may be readily varied so as to meet the requirements that .are presented by the work at hand.

Thus, while I have illustrated and'described the preferred embodiment of my invention, it is to be understood that this is capable of variation Thus I claim:

1. In an internal mix spray head adapted for use with a spray gun having a main air supply passage and a valve controlled supplemental air supply passage, said spray head comprising an outer member having an axial discharge orifice of round cross section formed therein and having a transverse slot formed in outer end of said member in a, plane passing through the axis of said orice, an inner member having a paint discharge nozzle formed ltherein and Ipositioned Vwithin said orice to cooperate therewith in delining an annular air passage about said nozzle for aspirating paint into said orifice from said nozzle, said inner member having passages therein adapted for connection with the main air supply passage of such a spray gun and to direct air to said annular air passage, a supplemental annular passage formed in said outer member and adapted to be connected to said supplemental air'supply passage of such a gun, said outer member having control passages connected to said supplemental annular passage and opening into said slot on opposite sides of said orifice and in a converging relation with respect to the axis of said orifice.

2. lIn an internal mix spray head adapted for use with a spray gun having a main air supply passage and a valve controlled supplemental air verse slot'formed in outer end thereof in a plane passing through the axis of said oriiice, said slot having an arcuate rear wall centered at a point falling on said axis forwardly of the slot, means affording a paint discharge nozzle disposed within said orifice to cooperate therewith in deiining an annular air passage about said nozzle for aspirating paint into said orice from saidnozzle, means providing passages adapted for connection with the main air supply passage of such a spray gun and toY direct air to said annular air passage, means providing a supplemental @passage adapted tobe connected to said supplemental air supply passage of such a gun, and means providing control passages connected to said supplemental passage and opening `into said slot on opposite sides of said orifice in a converging relation to the axis of said orice, said discharge passages opening into said slot through said rear wall substantially normal tothe rear wall at the,

points at which they open through said wall.

WILLIAM P. DALRYMPLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,029,423 Gustafsson Feb. 4, 1936 2,042,746 Tracy 'June 2, 1936V 2,082,061 -Jenkins June 1,'1937 2,102,303 Bramsen et al Dec. 14, 1937 2,214,035 Tracy Sept. 10, 1940 

